Subterranean termites present a serious threat to structures, and particularly residential structures, throughout most of the United States and in many parts of the world. One of the most widely used techniques to combat termite infestation is the application of chemical agents to the ground under and around the structure. In a typical preconstruction treatment situation, a liquid form termiticide is sprayed at specified concentrations and volumes directly onto the compacted soil immediately before the concrete slab is poured, creating a horizontal barrier between any subterranean nests and the underside of the slab. Additional barriers are created in by boring holes into the flatwork soil at specified intervals (often 12-18 inches) or by digging trenches around the structure and spraying termiticide into the openings as well as mixing termiticide with the backfill soil. If treatment is required to control active infestation that occurs after construction, techniques include drilling holes in infested walls and injecting liquid or powdered termiticides between the walls, boring holes in the floor slab at spaced intervals and injecting liquid termiticides into the soil, and trenching around the base of the structure and applying termiticides as in pretreatment. The termiticides used in these applications are usually repellants which help in keeping the termites away from the structures, but kill them if they try to enter. The disadvantage of this type of treatment is that it starts to break down as soon as it is subjected to sunlight and moisture when placed into the soil. Fipronil is labeled from most manufactures for many species of insects and wood destroying insects.
Termite shields have also been used to prevent termites or other damage causing insects from entering a structure. These have been basically been impenetrable barriers, sometimes impregnated with termite repulsing materials.